1. Field
The field of the invention is oil well drilling equipment and more particularly apparatus for preparation and handling of oil well drilling fluid.
2. Prior Art
The drilling process to tap underground reservoirs of oil involves the pumping of a high density, high viscosity, semi-fluid mixture of solids, water and other fluids, called "mud," downwardly through hollow drill stem segments and outwardly through passages provided in the drill head, by which it is cooled, lubricated and cleaned. The mud is forced by the pumping pressure upwardly around the drill stem through the drill bore and thence out of the well. The used mud is processed to remove entrained gases, sand and silt. It is then reconditioned by addition of finely divided solid materials to readjust its viscosity, density, and acid potential for reuse. Typically, the used mud is collected in a reservoir and then pumped at high pressure to form a jet through the bottom portion of an additive entrainment chamber. The finely divided solid additives are manually poured from bags into the chamber in a stream to be entrained by the high pressure jet. The additives tend to be introduced at non-uniform, erratic rates, so that the resulting mud composition, and its properties are insufficiently controlled. Recirculation and readjustment is often required to achieve proper mud properties. Since two or more additives are often required, the reconditioning by the present process is even more laborious, uncertain and time consuming.